The Katsumitsu school (勝光) grew within the workshops of province during their late- phase, the period that the trade calls , when the smiths of the village worked in a shared idiom and signed their blades with the day and month of their making. The name Katsumitsu was carried by more than a dozen smiths from the middle of the period onward, and the published sources single out those who cut a personal title above the : Ukyo-no- Katsumitsu, the senior of the line, and his son Jirozaemon-no-jo Katsumitsu, both counted among the most skilled of the makers and ranked beside Yosozaemon-no-jo Sukesada and Gorozaemon-no-jo Kiyomitsu as representative smiths of the late tradition. The line is inseparable from the Munemitsu branch, for Sakyo-no- Munemitsu was Ukyo-no-'s younger brother, and the two hands together produced the joint blades long prized under the name . The genealogy continues into Jirobei-no-jo Harumitsu, son of Jirozaemon-no-jo Katsumitsu, whose own dated work survives across the Eisho, Daiei and Kyoroku eras of the early sixteenth century.
The collective hand of the school is built on the open-waisted, double-structured , the and - line that is the diagnostic late- signature, set over a well-packed carrying and fine , in places a little standing or flowing. On the older and finer pieces a rises over this steel, while on the latest blades the classical reflection has largely gone, the itself looking powerful where the lies fine as dust. The work is -prevailing with , and entering richly, the clear and tightening, with small interspersed; the answers the , running to a or a pointed tendency with a turnback, and across both faces lie the devotional carvings of , a , with , and shrine names such as and Amaterasu Kotaijin, which the sources are careful to ascribe to collaborating horimonoshi rather than to the smiths' own hands. Within this shared - idiom the masters diverge by degree. The Katsumitsu hands mix into the most freely, the published record placing the conspicuous first in Katsumitsu and next in Munemitsu, for a more flamboyant effect than the plainer compound general to the group; Munemitsu, by contrast, holds an established reputation as a superior maker of , working a bright, smaller-scaled straight temper over an archaic-flavoured steel with standing . Harumitsu carries a quieter, more legible version of the opened , occasionally reaching back toward the older Oei- manner.
To a Katsumitsu blade is to weigh the high-grade chumon-uchi of the named masters against the bulk output of the Sukesada-era forges. The signed and dated pieces of the senior hands, with their bright -mixed , their command of a clear , and their fine devotional , mark the upper edge of late- workmanship; Fujishiro grades both Katsumitsu hands Jo-jo and Harumitsu at the Jo- level. The school's signed and dated work survives in fair number, and its standing rests on documented joint blades and special-order commissions: the joint with Yosozaemon-no-jo Sukesada, dated Eisho 18 and incised Hagun-no- and Sanshin-soku-ittai, commissioned by Ukita Yoshie and treasured as an heirloom of the Sendai Date family; the and , several forged on campaign at Kojima in and valued for the light they throw on the smiths' movements; and the joint Katsumitsu-Harumitsu and , prized as documentary material for the late genealogy. The patrimony runs through the Imperial collection, where blades signed Bishu Katsumitsu are kept as , through the joint inscribed Ichigo-ikkoshi held at Nogi Shrine, and through the old houses, each grounded in its own provenance. A signed Jirozaemon-no-jo or Ukyo-no- Katsumitsu, a dated Munemitsu, or a stout Harumitsu comes to market only from time to time, and a dated, devotionally carved example, the kind on which one smith once wrote that nothing could surpass it, is a rewarding thing for a collector of late to encounter.